Aluminum alloy-and-resin composite and method for making the same

ABSTRACT

An aluminum alloy-and-resin composite includes an aluminum alloy substrate, an anodic oxide film formed on the substrate, and resin composition bonded with the anodic oxide film. The anodic oxide film has nano-pores with an average diameter of about 30-60 nm. The resin composition fills the nano-pores and coatings surfaces of the anodic oxide film. The resin composition contains crystalline thermoplastic synthetic resins.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is one of the two related co-pending U.S. patent applications listed below. All listed applications have the same assignee. The disclosure of each of the listed applications is incorporated by reference into another listed application.

Attorney Docket No. Title Inventors US 33056 ALUMINUM ALLOY-AND-RESIN WEN-RONG COMPOSITE AND METHOD CHEN et al. FOR MAKING THE SAME US 33709 ALUMINUM ALLOY-AND-RESIN WEN-RONG COMPOSITE AND METHOD CHEN et al. FOR MAKING THE SAME

BACKGROUND

1. Technical Field

The present disclosure relates to composites of aluminum alloy and resin, particularly to an aluminum alloy-and-resin composite having high bonding strength between aluminum alloy and resin and a method for making the composite.

2. Description of Related Art

Adhesives, for combining heterogeneous materials in the form of a metal (such as light metals) and a synthetic resin are demanded in a wide variety of technical fields and industries, such as the automotive and household appliance fields. However, adhesives are generally only effective in a narrow temperature range of about −50° C. to about 100° C., which means they are not suitable in applications where operating or environmental temperatures may fall outside the range.

Therefore, other bonding methods have been applied that do not involve the use of an adhesive. One example of such methods is by forming bonds through injection molding or other similar process. However, the bonding strength of the metal and resin can be improved.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE FIGURES

Many aspects of the aluminum alloy-and-resin composite can be better understood with reference to the following figures. The components in the figures are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the aluminum alloy-and-resin composite. Moreover, in the drawings like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a cross-section view of an exemplary embodiment of a composite of anodized aluminum alloy and resin.

FIG. 2 is a scanning electron microscopy view of an exemplary embodiment of the anodized aluminum alloy.

FIG. 3 is a scanning electron microscopy cross-section view of the composite shown in FIG. 1.

FIG. 4 is a cross-section view of molding the composite shown in FIG. 1.

DETAILED DESCRIPTION

FIG. 1 shows an aluminum alloy-and-resin composite 100 according to an exemplary embodiment. The aluminum alloy-and-resin composite 100 includes an aluminum alloy substrate 11, an anodic oxide film 13 formed on a surface of the aluminum alloy substrate 11, and resin compositions 15 formed on the anodic oxide film 13.

The anodic oxide film 13 is formed by anodizing the aluminum alloy substrate 11. Referring to FIG. 2, the anodic oxide film 13 defines nano-pores 131. These nano-pores 131 have an average diameter of 30-60 nm. The nano-pores 131 are symmetrically distributed in the anodic oxide film 13.

The resin composition 15 may be coupled to the anodic oxide film 13 by molding. During the molding process, molten resin coats surfaces of the anodic oxide film 13 and fills the nano-pores 131, thus strongly bonding the resin composition 15 to the anodic oxide film 13. Compared to the conventional injection molding process using non-anodic film, the composite 100 in this exemplary embodiment has a much stronger bond between the resin composition 15 and the substrate 11 (about quintuple bonding force). The resin composition 15 may be made up of crystalline thermoplastic synthetic resins having high fluidity. In this exemplary embodiment, polyphenylene sulfide (PPS), polyamide (PA), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT) can be selected as the molding materials for the resin composition 15, and all of the resins can bond firmly with the anodic oxide film 13 and the substrate 11.

It is to be understood that auxiliary components may be added to the resins to modify properties of the composition 15, for example, fiberglass may be added to PPS. The fiberglass may have a mass percentage of about 10-50%.

FIG. 3 shows a scanning electron microscopy cross-sectional view of the composite 100. In FIG. 3, almost no cracks are observed between the resin composition 15 and the anodic oxide film 13, clearly demonstrating that the resin composition 15 tightly bonds to the anodic oxide film 13 and fills the nano-pores 131.

A method for making the composite 100 may include the following steps:

The aluminum alloy substrate 11 is provided.

The substrate 11 is degreased. The degreasing process may include the step of dipping the substrate 11 in a sodium salt solution for about 5-15 minutes. The sodium salt solution may include sodium carbonate having a concentration of about 30-50 grams per liter (g/L), sodium phosphate having a concentration of about 30-50 g/L, and sodium silicate having a concentration of about 3-5 g/L. The temperature of the sodium salt solution may be about 50-60° C. Once degreased, the substrate 11 is removed from the sodium salt solution and rinsed in water.

The surface of the substrate 11 is roughened. Roughening the substrate 11 may include the step of chemically etching. The chemical etching process may include the step of dipping the substrate 11 in an alkaline solution for about 1-2 minutes. The alkaline solution may include sodium hydroxide having a concentration of about 20-35 g/L, and sodium carbonate having a concentration of about 20-30 g/L. The temperature of the alkaline solution may be about 40-55° C. The chemical etching process roughens the surface of the substrate 11 so that it will be more uniformly anodized and to obtain a narrower range of diameters of the nano-pores 131 of the anodic oxide film 13. Next, the substrate 11 is removed from the alkaline solution and rinsed in water.

The substrate 11 is anodized to form the anodic oxide film 13. The anodizing process may be carried out in a sulfuric acid solution, with the substrate 11 being an anode, and a stainless steel board or a lead plate being a cathode. The sulfuric acid solution may have a concentration of about 100-250 ml/L. The electric current density through the sulfuric acid solution is about 0.5-4.9 A/dm². Anodizing the substrate 11 may last for about 15-60 minutes. Then, the substrate 11 is rinsed in water and then dried.

It is to be understood that the anodizing process can also be carried out in a phosphoric acid solution or an oxalic acid solution.

Referring to FIG. 4, an injection mold 20 is provided. The injection mold 20 includes a core insert 23 and a cavity insert 21. The core insert 23 defines several gates 231, and several first cavities 233. The cavity insert 21 defines a second cavity 211 for receiving the substrate 11. The anodized substrate 11 is located in the second cavity 211, and molten resin is injected through the gates 231 to coat the surface of the anodic oxide film 13 and fill the nano-pores 131, and finally fill the first cavities 233 to form the resin compositions 15, as such, the composite 100 is formed. The molten resin may be crystalline thermoplastic synthetic resins having high fluidity, such as PPS, PA, PET, and PBT. During the molding process, the injection mold may be at a temperature of about 120-170° C.

Tensile strength and shear strength of the composite 100 have been tested. The tests indicate that the tensile strength of the composite 100 is greater than 8 MPa, and the shear strength of the composite 100 is greater than 15 MPa. Furthermore, the composite 100 has been subjected to a temperature humidity bias test (72 hours, 85° C., relative humidity: 85%) and a thermal shock test (48 hours, −40-85° C., 4 hours/cycle, 12 cycles total), such testing did not result in decreased tensile strength and shear strength of the composite 100.

It is believed that the exemplary embodiment and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its advantages, the examples hereinbefore described merely being preferred or exemplary embodiment of the disclosure. 

1. An aluminum alloy-and-resin composite, comprising: an aluminum alloy substrate with an anodic oxide film having nano-pores with an average diameter of about 30-60 nm on its surface; and resin composition integrally bonded to the surface of the aluminum alloy substrate having the anodic oxide film, the resin composition filling the nano-pores of the anodic oxide film, the resin composition containing crystalline thermoplastic synthetic resins.
 2. The composite as claimed in claim 1, wherein the resin composition is formed by molding crystalline thermoplastic synthetic resin on the anodic oxide film.
 3. The composite as claimed in claim 1, wherein the crystalline thermoplastic synthetic resin is polyphenylene sulfide, polyamide, polyethylene terephthalate, or polybutylene terephthalate.
 4. The composite as claimed in claim 3, wherein the crystalline thermoplastic synthetic resin is polyphenylene sulfide added with fiberglass, the fiberglass has a mass percentage of about 10-50%.
 5. A method for making an aluminum alloy-and-resin composite, comprising: providing an aluminum alloy substrate; roughening the surface of the substrate; anodizing the substrate to form an anodic oxide film on the substrate, the anodic oxide film defining nano-pores having an average diameter of about 30-60 nm; positioning the anodized substrate in a mold and molding crystalline thermoplastic synthetic resin on the anodic oxide film and filling the nano-pores of the anodic oxide film to form the composite.
 6. The method as claimed in claim 5, wherein roughening the substrate includes the step of dipping the substrate in an alkaline solution having a temperature of about 40-55° C. for about 1-2 minutes.
 7. The method as claimed in claim 6, wherein the alkaline solution includes sodium hydroxide having a concentration of about 20-35 g/L, and sodium carbonate having a concentration of about 20-30 g/L.
 8. The method as claimed in claim 5, wherein anodizing the substrate is carried out in a sulfuric acid solution for about 15-60 minutes, the concentration of the sulfuric acid is about 100-250 ml/L, the electric current density through the sulfuric acid solution is about 0.5-4.9 A/dm².
 9. The method as claimed in claim 5, wherein anodizing the substrate is carried out in a phosphoric acid solution or an oxalic acid solution.
 10. The method as claimed in claim 5, wherein the crystalline thermoresin is polyphenylene sulfide, polyamide, polyethylene terephthalate, or polybutylene terephthalate.
 11. The method as claimed in claim 10, wherein the crystalline thermoplastic synthetic resin is polyphenylene sulfide added with fiberglass, the fiberglass has a mass percentage of about 10-50%.
 12. The method as claimed in claim 5, further comprising a step of degreasing the substrate before roughening the substrate.
 13. The method as claimed in claim 12, wherein degreasing the substrate comprises dipping the substrate in a sodium salt solution.
 14. The method as claimed in claim 13, wherein the sodium salt solution includes sodium carbonate having a concentration of about 30-50 g/L, sodium phosphate having a concentration of about 30-50 g/L, and sodium silicate having a concentration of about 3-5 g/L.
 15. An aluminum alloy-and-resin composite, comprising: an aluminum alloy substrate; an anodic oxide film having nano-pores with an average diameter of about 30-60 nm formed on a surface of the substrate, and resin composition integrally molded on the surface of the aluminum alloy substrate having the anodic oxide film, the resin composition filling the nano-pores of the anodic oxide film, the resin composition containing crystalline thermoplastic synthetic resins.
 16. The composite as claimed in claim 15, wherein the anodic oxide film and the nano-pores are formed by roughing and anodizing the substrate.
 17. The composite as claimed in claim 16, wherein roughing the substrate comprising the step of chemically etching the substrate.
 18. The composite as claimed in claim 17, wherein chemically etching the substrate includes the step of dipping the substrate in an alkaline solution having a temperature of about 40-55° C. for about 1-2 minutes.
 19. The composite as claimed in claim 18, wherein the alkaline solution includes sodium hydroxide having a concentration of about 20-35 g/L, and sodium carbonate having a concentration of about 20-30 g/L.
 20. The composite as claimed in claim 15, wherein the crystalline thermoplastic synthetic resin is polyphenylene sulfide, polyamide, polyethylene terephthalate, or polybutylene terephthalate. 